Attachment for hydraulically operated dental chairs and the like



De 8, 1936- s. H. RICHARDSON 2,063,122

ATTACHMENT FOR HYDRAULICALLY OPERATED DENTAL CHAIRS AND THE LIKE Filed Feb. 1s, 1955 3 Sheets-Sheet 1 7. 7 l N VENTOR. Jfm4@ f/eivg/ fF/charaon .1 TTORNEY.

- 1936- s. H. RICHARDSON ATTACHMENT FOR HYDRAULICALLY OPERATED DENTAL CHAIRS AND THE LIKE Filed Feb. 13, 1933 3 Sheets-Sheet 3 IN VE N TOR wary iic'idrdsm A TTORNEY Patented Dec. 8, 1936 UNITED STATES ATTACHMENT FOR HYDRAULICALLY OPER ATED DENTAL CHAIRS AND THE LIKE Stanley Henry Richardson, Detroit, Mich.

Application February 13, 1933, Serial No. 656,428

3 Claims.

My invention relates to an attachment for hydraulically operated dental chairs and the like and relates particularly to such an attachment adapted to convert a manually operated chair of this type into a motor actuated chair without requiring material alterations and changes in the chair structure.

Prior to my invention hydraulically operated chairs used principally by dentists and barbers have consisted essentially of a hydraulically actuated lift consisting of a piston reciprocable in a cylinder and moved therein by the pressure of a hydraulic fluid. The fluid is drawn from a fluid chamber or reservoir and pressures are built up upon the fluid by means of a manually actuated pump usually operated by a hand lever or a foot pedal. In the case of such devices used as dental chairs, it has been found to be impractical to operate the chair, either to raise or lower the chair, while the dentist is in the operating position facing the patient. The result has been that inconvenient and time-consuming operations are necessary in either raising or lowering the chair slightly from a position other than the operating position. Frequently it is necessary to make such adjustments several times before securing the proper position of the chair relative to the dentist.

Considerable time also is consumed in raising 3 chairs of the conventional type by the operation either of the hand lever or of the foot pump to build up the pressure upon the hydraulic fluid. Much of this time can be saved by an attachment embodying my invention.

The large number of. manually operated chairs now in use particularly in dental oflices and barber shops, may be motorized by means of an attachment embodying my invention. It is essential, however, that such attachments make suitable provision to limit the operation of theunotor automatically when the chair has reached a predetermined point in its upward movement.

It is, therefore, an object of my present invention to provide an attachment for hydraulically operated chairs and the like which is adapted to convert a manually actuated chair to a motor actuated chair without requiring material alterations in the structure of the chair.

It is a further object of my present invention to provide an attachment of this nature which permits operation of the chair from the operating position in such a manner that the chair may be moved to the required position without a loss of time incident upon the improper adjustment, of the chair.

It is a further object of my present invention to provide an attachment of this nature which is relatively inexpensive, simple in construction, positive in operation, and adapted to reduce the time consumed in operation of the chair to which it is attached.

It is a further object of my present invention to provide an attachment which is so constructed as to stop the movement of the chair automatically after it reaches a predetermined point in its upward movement.

These, and various other objects, features of arrangement, construction and operation, are plainly shown and described and will be best understood by reference to the accompanying drawings in which:

Fig. 1 is a fragmentary elevational view with parts broken away, showing an attachment embodying my invention secured to the pedestal base of a dental chair (not shown);

Fig. 2 is a section taken on the line 22 of Fig. 1;

Fig. 3 is a section taken on the line 33 of Fig. 1;

Fig. 4 is a plan view partially in section taken on the line 4-4 of Fig. 1;

Fig. 5 is a plan view of a motor base taken on the line 5-5 of Fig. l;

a Fig. 6 is a fragmentary section taken on the line 66 of Fig. 5;

Fig. '7 is a fragmentary elevational view with parts broken away, showing an automatically operated switch utilized in the construction of an attachment embodying my invention.

Fig. 8 is a fragmentary elevational view with parts broken away, showing a foot operated pump of a conventional design.

Fig. 9 is a sectional view taken on the line 9-9 of Fig. 8, showing'connection of the delivery conduit leading from the motor actuated pump.

Similar reference numerals refer to similar parts throughout the several views.

Referring more in detail to the drawings, and

particularly to Fig. 1, l0 designates the pedestal communicates with the interior of the chamber l3.

The specific details of this construction may vary in conventional types of such chairs, but the essential features of the telescoping supporting member |2 moved by fluid pressure built up in the chamber l3 by means of fluid under pressure passing through the conduit IE, will be found to exist in all known types of such chairs.

A manually operated chair of one conventional type includes a manually actuated pump connected with the conduit i6 and operated by means of a foot actuated pedal |1 (Figs. 4 and 8) which pump operates to force a hydraulic fluid under pressure through the conduit l6 and into the chamber l3 to cause movement of the supporting member !2. said fluid being drawn from the reservoir generally located in the base of the pedestal l3. Fig. 8 shows the details of construction of said pump, and referring thereto the same comprises a cylinder 80 in which there is slidably fitted a reciprocable piston 8| carried by the rod 82 adapted to engage a crank 83 secured to a suitably supported shaft having said foot pedal |1 secured thereto. In the bottom of said cylinder 88 there are provided two check valves- 84 and 85. Valve 84 is adapted to open into said cylinder 30 in opposition to the action of a coil spring 88, and it operates to admit the fluid into I said cylinder 89 through the conduit 81, valve chamber 88 and port 89 as the piston 8| rises creating partial vacuum in said cylinder. ball check valve 85 is adapted to open outwardly from the cylinder 80 in opposition to the action of a coil spring 5!] tending to maintain the ball valve in its closed position. Thus, alternative reciprocations of the piston 8| cause the fluid to open the valve 84 and enter said cylinder, valve 85 being closed. whereupon lowering of said piston causes closing of the valve 84 and opening of the valve 85. thus permitting the piston 8| to pump the fluid into the conduit 3| and therefrom through the conduit I6 into the chamber l3. Return movement of the piston 8|, caused by any suitable means such as by a spring (not shown) causes closing of the valve 85 and pumping acorresponding amount of fluid through the conduit 81 into the cylinder 80, as described, for the next succeeding delivery into the chamber l3.

Means for releasing the pressure in said chamber l3 and for draining the fluid therefrom thus permitting lowering of the chair, are usually exemplified by a release valve. such as a valve 93. In the structure shown, the valve 93 closes a drain hole 94 permitting the fluid to escape into the storage reservoir, and it is kept closed by the coil spring 95. By pressing a release pedal I8, the valve 93 is opened and the fluid passes from the chamber |3 into the storage reservoir, the size of the hole 94 determining the rate of said passing and, consequently, the speed at which the chair is lowered.

My invention resides in an attachment to chairs of the type just described. It attaches to such chairs without requiring reconstruction of the operating m chanism and does not interfere with the manually operated mechanism used to operate the fluid pump and to release the fluid from the fluid chamber.

The attachment embodying my invention consists essentially cf an electric motor 20 adapted to drive a constant pressure pump 2| through a drive pulley 22 secured to the shaft of the motor 20, and a driven pulley 23 secured to an operating shaft of the pump 2|, the drive being through a. belt 24. The pump 2| and the motor 20 are mounted on a base member 25, which is held in position relative to the pedestal base I0 by means of a removable band 28 clamped on the upper portion of the pedestal base ID. The band 26 is provided with lugs 21 and 28. Supporting arms 29' and 30 are secured to the base 25 and at one end are fastened to the lugs 21 and 28. A bracket 3| is secured to the arm 29 and provides a support fora valve 32. Secured to the base 25 between the pump 2| and the motor/20 is a sump 33, adapted to hold a. quantity of hydraulic fluid in addition to the quantity of hydraulic fluid contained in the fluid receptacle in the base of the pedestal. Fluid is withdrawn from the sump 33 by the pump 2| through a conduit 34, and is pumped under pres sure through a conduit 35. leading from the pump 2| to the valve 3'2.

A spring-pressed ball check valve 36 is unseated by the fluid under pressure from the conduit 35 and the fluid is permitted to enter the valve chamber 31. A conduit 38 leads from the valve chamber 31 and extends inside the pedestal base In to a point 39, where it connects with the conduit IS. A release valve 40 is placed in the valve chamber 31 and is provided with an extending rod 4|. A conduit 42 (Fig. 2) leads from the valve 32 to an adjustable check 43. A plug 42a, having a restricted opening therein, is placed in the conduit 42 at the point of connection with the valve 32. Fluid can pass through the conduit 42 only upon actuation of the release valve 40, the rate at which it can so pass being determined by the adiustment of the check 43.

A conduit 44 connects the check 43 with the sump 33 and permits a return of the fluid thereto. A conduit 45 is provided as a safety measure to carry away any surplus offluid in the sump 33 and to discharge it into the fluid reservoir (not shown) in the pedestal base I0. 4

As shown in Fig. 2, the conduit 42 leads from the valve 32 to the adjustable check valve 43. As here shown, the check valve 43 consists of a. casing 46 having a chamber 41 therein. A partition member 48 divides the chamber 41 into two portions, into one of which the conduit 42 is connected and from the other of which leads the conduit 44. A restricted opening 49 is. provided in the partition 48 and is regulated as to its size by an adjustable needle valve 50 seated therein. The release valve 40. is opened by movement of the rod 4|. Movement of the rod .4| is caused by a pivotally mounted arm 5|, which contacts with a rotatable shaft 52. Secured to the rotatable shaft 52 is. a release pedal 53, which is a'dapted to cause partial rotation of the shaft 52 when pressure is exerted on the pedal 53. As shownin Fig. 4 the shaft 52 is journaled in depending members 55 which are attached to lugs 54 carried on the removable band 26. In order to insure a tightness in the belt 2 at all times and a quietness in operation, the motor 20 is mounted on the base 25 in a cushioned mounting shown in detail in Figs. v5 and 6. As here shown, this mounting consists of a pair of horizontally extending members and BI and a pair of cross members 62 and 63. The base of the motor 20 is secured to the members 62 and 63 by bolts or similar means 64. The members 62 and 63 are connected with the members 80 and BI at the ends of the respective members. The members 60 and 6| are secured to the base 25 by bolts or similar means 69 passing through slots 65. Thus the entire motor support'is al- The members 60 and BI are secured to the members 62 and 63 at their ends by a cushioned mounting as shown in Fig. 6. This mounting consists of rubber washers 86 and 61 placed on the two sides of the members 62 and 63'. Bolts or similar means 68 extend through the rubber washers 66 and 61 and through the members 60 and El to secure the members 60 and GI in cushioned relation to the members 62 and 63. The members 60 and BI are secured to the base 25 by a plurality of bolts or similar means 69. With such a construction it is found that during operation the motor 20 tends to twist about its vertical axis. In so doing, the motor and mounting are thrown out of line. In order to neutralize this tendency, an extension 10 is provided on the end of the member 63 and a tension spring II is adjustably secured thereto and fixed to the member 5|. Adjustment of the tension in the spring 1| may be made through a screw-threaded hook I2 and nut 13. When properly adjusted, the spring 1| has sufficient tension to resist the twisting of the members 60, 6|, 62, and 63 due to the tendency of the motor 20 to twist about its vertical axis and so serves to hold the motor 20 in alignment.

The operation of the motor 20 is initiated by the foot switch 14 (Fig. 4) and may be stopped at any time by the same switch. To insure the stopping of the motor 20 when the chair is fully elevated, I provide an automatic safety switch mechanism shown in detail in Fig. '7, As here shown, the switch 15 is operated by a lever 16. The lever 16 is operatively connected with an operating arm 11. A stop 18 is secured to the outside of one of the telescoping supporting members I2 at a predetermined point and is adapted to contact with the end of the arm 11 asthe member |2 moves in an upward direction. When it reaches the end of its permitted upward movement, the lever 16 breaks the current and stops the motor 20.

The pump 2| shown in the drawings is a conventional constant pressure pump of any desired type, the pump shown in the drawings being of the rotating meshed gear type driven from a rotating shaft secured to the driven pulley 23.

The operation of my invention is as follows: When the chair is in its lowered position, foot pressure is applied to the switch 14. This starts the motor 20 which drives the pump 2| through the pulleys 22 and 23 and the belt *24. The sump 33 is filled with the hydraulic operating fluid and a portion thereof is withdrawn by the operation of the pump 2| which takes the fluid from the sump through the conduit 34. Pressure is built up on the fluid, and it is forced under pressure through the conduit 35 and the valve 32 to the conduit 38. It continues through the conduit |6 and is discharged, still under pressure, into the chamber l3. This exerts a pressure on the telescoping supporting member I2, This member is free to moveonly in an upward direction and this movement is initiated and continued during the time the pump 2| is in operation. When the pump 2| ceases to operate, the telescoping supporting member I2 is maintained in its extended position by the body of fluid in the chamber l3. This creates a back pressure on the fluid. The fluid cannot return further than the valve 32, where the spring-pressed ball check valve 36 has closed the opening of the conduit 35 and the release valve 40 is closed.

To lower the chair, the telescoping supporting member I2 is permitted to return toward its initial position by actuation of the release valve 40. This is accomplished by operation of the foot release pedal 53, which causes a partial rotation of the shaft 52 and movement of the arm 5|. This contacts the end of the rod 4| and opens the release valve 40. The fluid is then free to return through the valve 32 to the conduit 42 and through it to the check valve 43.

The adjustment of the needle valve 50 regulates the size of the opening 49 and determines the speed at which the amount of fluid can pass through the chamber 41 to the conduit 44 and its return to the sump 33. Thus the speed of the return of the chair may be regulated by adjustment of the needle valve 50.

To further regulate the rate of the return of the fluid to the sump 33, I provide the plug 42a at the point of connection between the conduit 42 and the valve 32. The restricted opening in this plug prevents the entire body of returning fluid impinging directly on the partition 48 of the check valve 43 and eliminates a knocking which otherwise may occur in the check valve 43.

If the switch 14 should be kept closed until the telescoping supporting member I2 has reached the safe limit of its upward travel, the member 78 contacts with one end of the arm 11 and raises the arm to such an extent as to move the lever 16 and break the flow of current to the motor 20. In the construction here shown, when this condition is set up, the motor 2|] is stopped and can be started again only by manual movement of the arm 11 in the downward direction and the actuation of the switch 15 to establish a connection to permit 2. flow of current to the motor 20.

While I have illustrated a preferred embodiment of my invention many modifications may be made without departing from the spirit of the invention, and I do not wish to be limited to the precise details of construction as herein set forth, but desire to avail myself of all changes within the scope of the appended claims.

Having thus described my invention, what I claim is new and desire to secure by Letters Patent of the United States is:

1. In an elevating chair, a base casing, a hydraulic jack and system mounted in the casing, a pedal operated pump housed in the casing and communicating with the system, a power driven auxiliary unit mounted externally of the easing and communicating with said hydraulic jack independently of said pedal operated pump and system, said unit comprising a power driven pressure pump, a sump communicating with said pump, communicating conduits leading from said pump to said jack and from said jack to said pump, and check valves in said conduits externally of said base casing controlling the flow of fluid to and from said jack through said conduits.

2. In an elevating chair, the combination of a base casing, a hydraulic jack and system mounted in the casing, a pedal operated pump housed in the casing and communicating with the system, a power driven auxiliary unit mounted externally of the casing and communicating with said hydraulic jack independently of said pedal operated pump and system, said unit including a motorized pump, a sump for containing the hydraulic fluid operatively connected with said pump, a feeding system operatively connecting said motorized pump to said jack and including a valve chamber,

a spring-pressed ball check and a manually oper able release valve adapted to release pressures within said chamber, a conduit leading from said pump to said valve chamber, said ball check closing said conduit and adapted to be unseated by predetermined pressure therein, thereby allowing the fluid to enter said chamber, a second conduit leading from said valve chamber to said jack, a foot actuated lever for releasing said release valve, a switch adapted to control the operation of said motorized pump, a safety switch actuated by said jack and adapted to control the operation of said motorized pump, and an adjustable restriction operatively connected with said release valve and adapted to control release of pressures from said release valve, thereby to regulate the speed of return of said jack.

3. In an elevating chair, the combination of a base casing, a hydraulic jack and system mounted in the casing, a pedal operated pump housed in the casing and communicatiing with the system, a power driven auxiliary unit mounted externally of the casing and communicating with said hydraulic jack independently of said pedal operated pump and system, said unit including an electrically operated motorized pump, a sump for containing the hydraulic fluid operatively connected with said pump, a feeding system operatively connecting said motorized pump to said Jack and including a valve chamber, a conduit leading from said valve chamber to said jack, a pressure release valve in said chamber, a foot actuated lever adapted to release said release valve, a switch adapted to control the operation of said motorized pump, a stop switch mounted externally of said base casing and actuated by said. jack to limit the upward movement of said jack including a lever adapted to be actuated by said jack to break an electrical circuit and stop operation of the motor after the said chair reaches a predetermined point in its operation, and an adjustable restriction operatively connected with said release valve and adapted to' control release of pressures from said release valve, thereby to regulate the speed of return of said jack.

STANLEY HENRY RICHARDSON. 

